PAF is a very progressive thinking air force which has always kept up with the cutting edge of technology. There is an internal debate happening in PAF already about the battlefield application and utility of 5th generation systems. Pakistan calculates its threats according to a software database called 'Threat Matrix'. If our threat level goes high when India brings in the T-50, the PAF will certainly look for a 5th gen platform. I think it would make good sense for PAF to join this program because it uses the same class of engines as the JF-17s which will make it easier and cheaper to operate a sizeable fleet. Also, i have heard 'rumors' that the sensor fusion developed for J-20 will be watered down and installed in further blocks of JF-17s too. If that materializes than it means that if PAF goes after J-31 and sensor fused JF-17s than our entire fleet would have brilliant situational awareness and unparalleled connectivity which the IAF can only dream of since they would be operating jets from 3 different suppliers who won't allow their sensors to be fused with other vendors for the fear of spying and technology concerns.